1. Field of the Invention
The present invention relates generally to integrated circuits, to integrated circuits assembled on circuit boards, and specifically to circuit boards containing more than one integrated circuit. More particularly, the present invention relates to apparatus and methods for testing the integrity of the interconnectivity between ones of the integrated circuits on the circuit board and for testing the functionality of analog integrated circuits assembled on circuit boards.
2. The Prior Art
Major portions of the manufacturing yield problem in electronics manufacturing are associated with the assembly process. It has been suggested that over 80% of the problems are related to missing and/or misplaced components and faulty integrated circuit interconnections. Less than 20% of the assembly yield problems are related to integrated circuit problems.
Numerous methods for testing integrated circuits and for testing assembled circuit boards exist in the prior art. Individual components may be tested by IC testers, and, when installed on a circuit board, digital integrated circuits may be tested by using boundary scanning techniques such as those described in the publication Standard Test Access Port and Boundary Scan Architecture, IEEE Standard 1149.1. Circuit boards may be tested using bed-of-nails testers and other manufacturing test equipment. As circuit board densities increase, bed-of-nails testing becomes a less viable alternative for several reasons.
Another problem which confronts the electronic industry is the testing of analog integrated circuit networks. Analog components and networks introduce significant disarray into self-test schemes. Unlike digital components and networks, it is difficult to utilize a single approach for testing the validity and functionality of analog components and networks. Known digital boundary scanning techniques are not applicable to testing in the analog environment.
It is an object of the present invention to provide an improved apparatus and method for testing integrated circuits and assemblies of integrated circuits, such as assembled circuit boards.
Another object of the present invention is to provide apparatus and methods for testing integrated circuits which eliminates as much as possible the use of manufacturing test equipment.
It is yet another object of the present invention to build self-testing capabilities into the assembled product itself.